In recent years, electronic devices equipped with multiple light-emitting sources, such as a light-emitting diode (LED) for incoming call and an infrared sensor, have become popular. The electronic devices equipped with multiple light-emitting sources include, for example, a cellular phone (a smartphone), a tablet personal computer (PC), and the like.
More specifically, such an electronic device includes a housing on which a first hole corresponding in position to an LED and a second hole corresponding in position to an infrared sensor are formed. The electronic device further includes an LED light guide plate that has a first projection to be inserted into the first hole of the housing and guides light of the LED from the first projection to the first hole. The electronic device still further includes an infrared-sensor light guide plate that has a second projection to be inserted into the second hole of the housing and guides light of the infrared sensor from the second projection to the second hole.
A double-sided tape is inserted between the LED light guide plate and the housing to fix the LED light guide plate to the housing and prevent intrusion of water or the like into the housing. Furthermore, a double-sided tape is inserted between the infrared-sensor light guide plate and the housing to fix the infrared-sensor light guide plate to the housing and prevent intrusion of water or the like into the housing. Namely, the LED light guide plate and the infrared-sensor light guide plate are attached to the housing via the separate double-sided tapes, respectively.
Patent document 1: Japanese Laid-open Patent Publication No. 2011-068123
However, the conventional structure is not designed to maintain the light blocking effect while securing an attachment region of an adhesive member inserted between a light guide plate and a housing.
Namely, with the miniaturization of recent housings, it is often the case that an LED light guide plate and an infrared sensor are proximally placed. Therefore, in the conventional structure where the LED light guide plate and the infrared-sensor light guide plate are attached to the housing via the separate double-sided tapes, an attachment region of each of the double-sided tapes becomes narrower with the miniaturization of the housing. As a result, it may become difficult to secure respective attachment regions of the double-sided tapes inserted between the light guide plates and the housing.
If an attachment region of the double-sided tape is excessively narrow, the double-sided tape is likely to come off from, for example, the LED light guide plate or the housing, and thus light of the LED could come out through a gap between the double-sided tape and the LED light guide plate or the housing. Consequently, the light blocking effect may be deteriorated.